I don't agree with storing values as separated lists.

But, to answer your question, I have made the assumption that TB_CongVan is the parent table, and cap2 is the child table.

SELECT

cv.SoCV

, ReadUser = cv.ReadUser + ISNULL('|' + cap.ReadUser, '')

FROM dbo.TB_CongVan AS cv

LEFT JOIN (

SELECT

SoCV

, ReadUser = LTRIM(RTRIM(STUFF((

SELECT '|' + d.ten

FROM dbo.cap2 AS d

WHERE c.SoCV = d.SoCV

ORDER BY d.id

FOR XML PATH('')

), 1, 1, '')))

FROM dbo.cap2 AS c

GROUP BY c.SoCV

) AS cap

ON cv.SoCV = cap.SoCV;